1. Technical Field
The present disclosure relates generally to contact image sensing modules, and more particularly to a contact image sensor module with an improved glass plate and an improved light source.
2. Description of Related Art
It is well known that contact image sensors are cheap and easy to build, compared with charge couple devices, and are highly competitive in the low resolution and low price markets, such as home scanners and fax machines. A contact image sensing module of a scanner works by directing light emitted from a light source onto the scanned document, and then the light is reflected from the document onto a lens unit. The reflected light is then focused through the lens unit to form an image in a contact image sensor, and thus corresponding image signals are generated.
Usually, a glass plate is utilized to improve a uniformity of the light on the document. However, the glass plate is generally cuboid with an emitting surface and an incident surface formed at two opposite sides thereof, respectively. The light source is arranged below the glass plate and near a side of the glass plate. Thus a large distance must be kept between the glass plate and the light source for obtaining desired uniformity of the light through the glass plate. Thus the contact image sensing module occupies a large space, which conflicts with the requirement for light weight and compactness.
What is needed, therefore, is a contact image sensing module which can overcome the above limitations.